China has held its largest military drills in the hotly contested South China Sea, according to the country’s Defense Ministry, culminating in a naval parade Thursday overseen by Chinese President Xi Jinping.

At least 10,000 personnel took part in the drills, which involved 48 naval vessels and 76 fighter jets, the ministry said.

China’s only aircraft carrier, the Liaoning, took part in the parade with a display of J-15 fighter jets under Xi’s observation.

Chinese President Xi Jinping reviews a naval parade Thursday in the South China Sea.

The South China Sea has long been a flashpoint in Asia. The Chinese government claims a huge swath of territory across the sea, overlapping with claims of the Philippines and Vietnam, among others.

The massive PLA navy drills in the South China Sea sent a clear signal to the other claimants in the region, as well as the United States, Collin Koh, research fellow at the S. Rajaratnam School of International Studies’ Maritime Security Program, told CNN. “The PLA Navy is there and they’re there to stay,” he said.

Though both Taipei and Beijing view the island as part of China, neither government recognizes the legitimacy of the opposing side, with Beijing warning that it could retake the island by force if necessary.

Xi had a blunt message for Taiwan during a nationalistic speech at the conclusion of the China’s National People’s Congress in March, where he warned against any attempts to “split the motherland.”

“Every inch of our great motherland’s territory cannot be separated from China,” he said, drawing loud applause from his audience inside the Great Hall of the People.

US tensions over trade

The Chinese exercises are taking place amid rising tensions between Beijing and Washington over trade, but analysts have also expected the Trump administration to harden its policy on the South China Sea.

A US aircraft carrier, the USS Theodore Roosevelt, arrived Wednesday in Manila, Philippines, for what was described as a “scheduled port visit.”

The US Navy recently conducted several “freedom of navigation” operations with warships sailing near increasingly militarized man-made Chinese islands in the South China Sea, triggering strong protests from Beijing.